The principle of graduality is a classic tool of the modernists. Annibale Bugnini sold it to Pope Pius XII; and as a consequence, eventually all of the rites of the Sacraments, not only the Mass, have been gradually replaced by the new, illicit ones. Pope Paul VI, riding on the wave of the Pastoral Council, altered the Sacrament of Order first. He did this so that the new Conciliar sect would have a different hierarchy, ordained into the new rite with an alternative understanding of priesthood and episcopacy. Since the sacred had to be eliminated, the rite of episcopal consecration was invalidated in its essential-for-validity form and the intention of the minister. In a more deceptive way, the same was done to the ordination of a priest. As a result, today we see a different entity from The One, Holy, Catholic and Apostolic Church.
For a cleric to be a part of the Church, he has to cross the threshold of the rite of Holy Order. As a general rule, the rite of Baptism bestows upon a Catholic the rights and privileges associated with membership in the Church. Fr. Vigano enjoyed the rights and privileges of the Roman Rite until his invalid "consecration" to the episcopacy in the rite to which he was artificially introduced. He crossed the threshold into the Conciliar sect. He lived in the Matrix of the New Advent. By the grace of God, he realized what was happening to him before he was called to give the testimony of his life. Now he has a chance to repent, confess, and repair what is in his power. The longer he waits with his announcement, the higher the possibility of the souls affected by him (the Pope, bishops, priests, and faithful) arriving at their judgement day without being fortified by the Sacraments of the Church.
Yes, graduality is a classic modernist method...